CN103202526B - Water adding and dispersing regulating method for smoked sheet damping machine of high-inertia system - Google Patents

Abstract

The invention discloses a water adding and dispersing regulating method for a smoked sheet damping machine of a high-inertia system. The method comprises the steps of: 1, adding water in advance to estimate, i.e. performing water adding control on tobacco leaves at the first blanking according to a water adding estimation function through a system, and detecting whether the tobacco leaves are output from a tobacco leaf damping barrel or not, so as to judge the first blanking is finished or not; 2, discrete sampling: after entering a normal production state, sampling water from an outlet at fixed time, and recording the sampling value F(t) of the water from the outlet every 10 seconds; and 3, trend comparing and regulating: during sampling, comparing a current water value x with the recorded sampling value F(t) of the water from the outlet in real time, and thus determining the changing trend of the current water. After the method is adopted, the system can obtain certain foreseeability on water variation according to the changing trend of the current water, so that the adjustment sensitivity of the system is increased, a continuous oscillating outlet water condition which is caused by a traditional regulating method is effective reduced, and the high inertia and large hysteresis quality of the system can be overcome to a certain degree.

Description

Discrete water-adding adjustment method for large-inertia system smoke sheet dampening machine

technical field

The invention relates to the field of automatic control of tobacco processing equipment, and is a discrete control method suitable for a control system with large disturbance and large inertia link, in particular, a water-adding discrete adjustment method for a tobacco sheet moistening machine.

Background technique

With the continuous improvement of the automation control degree of the tobacco production line, the control indicators of the production equipment are becoming more and more strict. The tobacco sheet moisture rejuvenation machine is the second key process point of the silk production line after the slicing machine. Its function is to add water and steam to the sliced flue-cured tobacco block to realize the loosening, heating and moisture regain of the material. Among them, the moisture regain The final material moisture value is the most critical process index. The main principle of the water adding system of the damp conditioner is to adjust the amount of water added to the damp conditioner so as to control the moisture content of the material. The water adding system of the moisture conditioner is a large disturbance system disturbed by many factors, including: the type and composition of the material to be processed, the width of the cigarette bale slices and the difference in moisture between cigarette bales, etc.

The traditional negative feedback control method (Fig. 1) is used for the traditional water addition control of the moisture resurfacing machine. First, a moisture index (SP) is artificially set, and the system samples the actual moisture value (PV) at the outlet of the moisture reconditioning machine. The deviation (SP-PV) between the water content value and the water content set value, and then adjust the opening (CV) of the water adding membrane valve, so that the actual water content value approaches or equals the water content set value. Among them, the system control volume (CV) is continuous and changes constantly according to the size of the deviation. The traditional feedback control method has the characteristics of quick response and high system sensitivity, so it is very effective in the system with small inertia and fast response. However, the water adding system of the moisture conditioner is a system with large inertia, slow response speed and many interference factors. The entire response time from changing the water addition to the change of the outlet material moisture is as long as 5 to 7 minutes. Therefore, the traditional negative feedback control method makes the system oscillate continuously for a long time, and the outlet moisture cannot be stabilized.

Contents of the invention

The water-adding discrete adjustment method for the tobacco sheet dampening machine disclosed by the present invention is a discrete control method suitable for a large disturbance and large inertia system. The so-called discrete control method means that the system control quantity is adjusted discontinuously. Under normal circumstances, The control quantity keeps a certain value during the production process, and only when the system meets certain conditions, the control quantity changes. This adjustment method can properly reduce the response speed of the system and better adapt to the system with large inertia and large lag. Avoid the continuous oscillation of the system and make it unstable.

Described method has three steps to the regulation of moisture, is described in detail respectively below:

Step 1 pre-adding water is estimated,

The moisture conditioner only has a moisture meter at the outlet, so when the conditioner is in the head material stage, there is no material at the exit of the conditioner, so the moisture value fed back is not the real value, which makes it impossible to use feedback to adjust the amount of water added. Therefore, when the moisture regainer is in the head material stage, we designed a water addition function with time as the independent variable. This function is the pre-water estimation of the system. The pre-water estimation is divided into two stages:

Stage 1. The system estimates the function based on water addition: water addition setting value (kg/h) = inlet material flow rate (kg/h) × (moisture content setting value%-C1)/(C2-moisture content setting value%)× The water addition coefficient C, wherein the value of the constant C1 is 12, the value of the constant C2 is 100, the value range of the water addition coefficient C is 0.2-0.5, and the value of the water content % is 17.5%. water control;

Phase 2: Detect whether there are tobacco leaves output from the tobacco sheet reconditioning cylinder to judge whether the end material state is over. If not, continue to step one. The water addition estimation function in stage 1 adjusts the water addition amount according to the reading of the moisture meter until the outlet moisture of the system reaches the target setting value of 17.5%. At this time, the system records the current water addition amount and keeps it, and detects the current moisture value x , and at the same time switch the system to the discrete regulation state, proceed to step 2;

Step 2, discrete sampling:

The sampling value mentioned here means that the system performs data sampling on the value of the outlet moisture meter at intervals T.

Figure 2 is a trend diagram describing the change of outlet moisture with time, where e(t) is the outlet moisture value; the horizontal axis t is time; T is the sampling period; τ is the sampling time. The broken line is the continuous function of the water content of the leaf outlet changing with time, and the black dotted line is the curve smoothed by the five-point cubic smoothing method after the system has been sampled, that is, the non-linear continuous function that changes with time is equivalent to a discrete " linear" function.

The advantage of using discrete sampling is that the system can grasp the general trend of water content, reduce the impact of disturbance and noise on the system, and enable the system to be adjusted more effectively.

Step 3. Trend comparison and adjustment:

The trend here mainly refers to the change direction (increase or decrease) of the dependent variable (exit moisture). We compare the current outlet moisture data X with the sampling value F(t) to determine the direction and trend of moisture change at this time.

1. When x-F(t)>n, it means that the outlet moisture is increasing;

2. When x-F(t)<-n, it means that the outlet moisture is decreasing; the value range of n mentioned above is 0.02-0.05, which can be artificially corrected according to the actual situation.

The water addition system will analyze the water addition trend in real time, and judge whether to adjust the water addition amount or keep the current water addition amount unchanged according to the water content change trend. The value of n is related to the disturbance and inertia of the system, and each system is different. These values are generally given in system debugging. As mentioned above, the system has stored a memory value in the second stage of estimating water addition. Based on this value, the system will carry out negative feedback adjustment with the target moisture value, and the adjustment range can be adjusted manually according to the actual situation.

After adopting this method, there is a certain degree of predictability to the change of water content, which increases the adjustment sensitivity of the system, effectively reduces the situation that the outlet water content continuously fluctuates up and down caused by the traditional adjustment method, and overcomes the existence of the system itself to a certain extent. The large inertia and large hysteresis have greatly improved the process quality score of the outlet water.

Description of drawings

Fig. 1 is a block diagram of a traditional moisture regainer water adding control method;

Figure 2 is a trend diagram of the change of moisture at the outlet of the moisture conditioner with time;

Fig. 3 is a control flowchart;

Fig. 4 is a block diagram of the control system of the present invention.

Detailed ways

The present invention is described in detail in conjunction with the control flow diagram 3 and the system block diagram 4 as follows.

Step 1 is divided into two stages:

Stage 1. The system estimates the function based on water addition: water addition setting value (kg/h) = inlet material flow rate 2400 (kg/h) × (moisture content setting value 17.5-constant 12)/(constant 100-moisture content setting value 17.5) × water addition coefficient 0.3 to calculate the amount of water added, and control the water addition to the tobacco leaves in the head state;

Stage 2: PLC programmable controller 1 detects whether there is any material 3. Tobacco leaves are output from the sheet reconditioning cylinder to determine whether the state of the top material is over. If not, continue to step 1. When there are tobacco leaves output from the tobacco sheet reconditioning cylinder, it is the top material When the state is nearing the end, the system continues to adjust the water addition amount through the water addition film valve 2 according to the water addition estimation function of stage 1 according to the reading of the moisture meter 4 until the outlet moisture of the system reaches the target setting value of 17.5%. At this time, the system maintains the current The amount of water added, and switch to the discrete adjustment state, proceed to step 2;

Step 2: After the end of the head material state and entering the normal production state, the system starts to regularly sample the outlet moisture, and records the outlet moisture sampling value F(t) every 10 seconds. After the next sampling cycle arrives, the system will The share value is rewritten into F(t), and the previous data is updated.

Step 3: While sampling, the system compares the current moisture value x with the recorded outlet moisture sampling value F(t) in real time to determine the current moisture trend.

a) When the water content x>17.8, and x-F(t)>0.03, it means that the outlet water value is on the rise. At this time, the set value of water addition is increased by 10kg/h every 10 seconds. If x-F(t)<0.03, The set value of the amount of water added remains unchanged at the current value;

b) When the water content x<17.8, and x-F(t)<-0.03, it means that the outlet water value is in a downward trend. At this time, the set value of water addition is reduced by 10kg/h every 10 seconds. If x-F(t)>0.03 , the set value of water addition keeps the current value unchanged;

c) When the water content x satisfies 17.3<x<17.8, the set value of the amount of water added remains unchanged at the current value.

In the application example, since the ideal value of outlet moisture is 17.5%, we need the moisture to remain stable in an interval around 17.5, so the amount of water added will be adjusted in the interval of moisture x>17.8 and x<17.3 , while in the interval from 17.3 to 17.8, the amount of water added remains unchanged to avoid water shocks caused by frequent changes in the amount of water added.

Claims (2)

1., for the discrete adjustment method that adds water of Great inertia system tobacco flake steam conditioner, comprise the steps:

Step one adds water estimation in advance, is divided into two stages:

Stage one, system are according to the estimation function that adds water: the setting value that adds water (kg/h)=entrance mass flow (kg/h) × (moisture content setting value %-C1%)/(C2%-moisture content setting value %) × add water coefficient C, wherein constant C1 value is 12%, constant C2 value is 100%, the span adding water coefficient C is 0.2-0.5, moisture content setting value % value is 17.5%, adds water management in head material state to tobacco leaf;

Whether stage two, detection have tobacco leaf to export from smoked sheet ordering cylinder, to judge whether head material state terminates, step one is continued if do not terminate, when there being tobacco leaf to export from smoked sheet ordering cylinder and at the end of head material state closes on, system continues to regulate amount of water according to moisture teller reading according to the estimation function that adds water in stage one, until the outlet moisture content of system reaches target set point 17.5%, now current under system log (SYSLOG) amount of water also keeps, and detect current moisture content value x, simultaneously by systematic evaluation to discrete adjustment state, carry out step 2;

Step 2 discrete sampling: head material state terminates, after entering normal production status, system starts to carry out timing sampling to outlet moisture content, every 10 seconds, record moisture content of outlet sampled value F (t), after the next sampling period arrives, moisture content value re-writes in F (t) by system, upgrades previous data;

Step 3 trend is to when regulating: while sampling, moisture content of outlet sampled value F (t) of current moisture content value x and record is carried out real-time comparison by system, in order to determine the variation tendency of current moisture content, as x-F (t) >n, illustrate that outlet moisture content increases; As x-F (t) <-n, illustrate that outlet moisture content reduces; System is according to the variation tendency of current moisture content, and adjustment amount of water setting value in real time, the span of n is 0.02-0.05, artificially revises according to actual conditions.

2., as claimed in claim 1 for the discrete adjustment method that adds water of Great inertia system tobacco flake steam conditioner, it is characterized in that, when carrying out step 3, point three kinds of state adjustment amount of water setting values:

A) as moisture content x>17.8, and during x-F (t) >0.03, indicate saliva part value and be in ascendant trend, now amount of water setting value reduces 10kg/h in every 10 seconds, if x-F (t) is <0.03, amount of water setting value keeps currency constant;

B) as moisture content x<17.3, and during x-F (t) <-0.03, indicate saliva part value and be in downward trend, now amount of water setting value increases 10kg/h in every 10 seconds, if x-F (t) is >-0.03, amount of water setting value keeps currency constant;

C) when moisture content x meets 17.3<x<17.8, amount of water setting value keeps currency constant.